Seeding implements typically include a seed supply system that takes seed from a storage container and conveys the seed to a furrow made in the ground surface by a furrow opener of the implement.
When seeding, it is desired to plant the seeds to obtain a selected plant population with a selected number of plants growing in a given area, such as X plants per square meter. In order to obtain this desired plant population, a seeding rate is determined, commonly in units of weight per given area, such as pounds per acre. For any seed variety, a pound of seed will contain approximately a known number of seeds. The number of seeds per pound will of course vary, depending on seed size, density of the seed, moisture content, and like variable characteristics of the sample compared to the seed standard, but for a great many seeds, typically small seeds such as wheat, barley, canola, using a rate in pounds per acre provides satisfactory plant populations.
The germination rate of the seed will also be determined to determine what percentage of the seeds being sown are viable and will grow into a plant. Such germination rates can vary considerably, and so where germination rate is lower, an increased application rate will be required.
Ideally, the plants will be evenly distributed along the furrow so that each plant has the same optimum space for growth. Evenly spaced plants provide maximum yields, and mature evenly. Uneven spacing also wastes seed, which is becoming increasingly expensive. The benefits of along-the-row seed separation uniformity are well known and practiced on row crop planters for crops such as corn and sunflowers, where singulator mechanisms have been developed to drop seeds into a furrow one at a time at constant intervals in order to provide uniform seed spacing in the furrow.
Such row crop planters typically plant fairly widely spaced parallel rows of seed, for example 24 inches or 36 inches apart. Conventional row crop planters have typically included a number of spaced apart seeding assemblies, each with a storage container to carry seed, and a furrow opener. A singulator type metering device at the bottom of the storage container takes seeds one at a time and drops them into the furrow created by the furrow opener.
In conventional solid seeding implement, the row spacing is much reduced, typically 6-12 inches between rows. Conventionally a single container extends across the width of the seeder above the furrow openers, and metering devices, such as a rotating feed wheels, are provided in the bottom of the container above each furrow opener to meter seed from the container to the furrow opener.
While it is contemplated that many solid seeded crops could also benefit from increased uniformity of seed spacing, the rows are much closer together and providing conventional singulating technology, which often include vacuum pick ups, on each furrow opener would be too complex and too expensive to be warranted. These conventional singulating systems are quite time consuming to adjust and to clean out when changing seeds and also do not readily adapt to a variety of seed sizes and spacing requirements that are encountered in solid seeded crops where seeds can be quite large as in wheat seeded at 100 pounds per acre, or quite small as in canola seeded at 4 pounds per acre.
Air seeders have become increasingly popular for all kinds of seeding. In air seeders, the seed is stored in a central bulk tank and then carried by an air stream to furrows made by furrow openers of the air seeder. In the majority of conventional air seeders, typically used for solid seeded crops, seed is metered from the tank into a distribution network of tubes and manifolds that divide the air stream eventually into a separate tube for each furrow opener. Sufficient seed is metered into the air stream to provide the desired seeding rate across the width of the air seeder. The distribution network is designed such that the air stream, and the seeds carried in the air stream, are divided substantially equally so that about the same amount of seed is delivered to each furrow opener, at least within a satisfactory range of variation.
The quantity of seed directed to each row will vary within a range that is considered acceptable, but still can be significant. There is also some degree of seed damage caused by the impact of seeds within the manifolds used to divide the air stream.
It is also known to meter seed from the tank directly into a separate tube for each furrow opener, and to carry the seed from the tank to the furrow opener with an air stream through each tube. Improved uniformity of seed distribution between rows, and reduced seed impact and resulting damage is thus achieved. Due to differences in individual seed friction within a tube, chance contacts within the delivery tube and air pulsing effects, the accurate metering rate will, however, not yield an even seed spacing when the seed exits the tube into the furrow even if the seed is singulated into the leading end of the tube.
Air seeders have also been developed for singulating seeds. Seed is pneumatically conveyed through tubes on demand to small secondary storage chambers above the individual furrow openers, and the seed in the secondary chambers is then metered to the furrow through a singulating mechanism. This type of distribution system is typical on newer row planters for corn, sunflowers, and the like. These singulating mechanisms are substantially the same as the conventional singulating mechanisms described above and have the same time consuming adjustment and clean out and also do not readily adapt to a variety of seed.